Method of making carborundum structures



' t0 hjoined June 15 1926. 1,588,473

J. KELLEHER METHOD MAKING CARBORUNDUM STRUCTURES Filed Oofi. 10, 1925@31 1 Gwen @013 Patented June 15, 1926.

' UNITED STATES" JAMES KELLEHER, OF CHIPPAWA, ONTARIO, CANADA, A SSIGNORTO HARPER ELE C- TRIO FURNACE CORPORATION, A CORPORATION OF NEW YORK.

METHOD OF MAKING CARBORUNDUM- STRUCTURES.

'Applicatton filed October 10,1925. Serial No. 61,683.

This invention relates to a method of making carborundum structures.

lVhile my invention may be embodied in a variety of forms, in itspreferred embodiment it is applied to the manufacture of monolithiccarborundum linings for the in-- terior of furnaces such as the liningof the combustion or heating chamber of a rever beratory furnace. Suchlinings serve to conduct heat to the mufile and at the same timepreventescape of any gas fromthe heat ng chamber to the -muflie chamber.lining of this character which is free'from joints or cracks is, ofcourse, desirable. -When, however, attempts have been made to make sucha lining without joints or cracks by mak-,

nace, preferably in such a manner that the.

surface of contact is at right angles to the flow of heat in thefurnace, and if a small amount of loose silicon carbide mix be placedbetween the two pieces, then upon heating the material to therecrystallizing temperature these two pieces will be found to be joinedtogether, apparently by a growth of crystal from one piece to the other.In this manner large and complicated sections may be built up. 1

While a carborundum mix such as coke, sawdust and sand may be usedbetween the surfaces which it is desired to join, this is notabsolutelyessential as fine carborundum grains Wlll act in a similarmanner, and in;

fact if two pieces of carborundum ware re crystallized, or-to berecrystallized, be placed in the furnace in close proximity without anybonding material whatever, a union may be effected. I. however,preferably use some bonding material. To effect the union I find that itis preferable to have'a certain amount of carbon present and theatmosphere in which the pieces are heated should be non-oxidizing. Thetemperature to which they are heated should be a proximately 18009 C. orover. W'hile have mentioned a recrystallizing furnace as the furnace inwhich the heating is efiected, it is obvious that furnaces of otherkinds may be em loyed.

In eating green ware for the purpose of recrystallizing the same, it iscustomary to embed the ware in carborundum mix. lVhen' large structuresof more or less complicated form are made by joining portions of thestructure in the manner above described, it is preferable torecrystallize the various parts of the structure before joining theparts to ether, because this avoids the necessity o embedding the entirestructure in mix. When the'recrystallized parts" are joined, I may thenembed merely the joint in the mix.

In the accompanying drawing, which il-' lustrates one way in which myinvention may be carried out, Fig. 1 is a diagrammatic sectional view ofa portion of the interior of a recrystallizing furnace, showing a.

heater and two plates ofcarborundum in position to be joined to oneanother.

Fig. 2 is a diagrammatic transverse section taken on the line 22 of Fig.1 and Figs. 3 and 4 are views similar respectively to Figs. 1 and 2, butshowing four carborundum plates in position to be joined to form amufiie open atthe ends.

The recrystallizing furnace contains a heating element d surrounded bycarborundum mixture which 'is composed of coke, sand and sawdust in theproper proportions and the articles to be recrystallized are placed inthe proximity of the heating element d so that when the furnace has beenrun the crystalline form of carborundum will surround the article to berecrystallized as shown by the dottedline e. If now, as m the case ofFigs. 1 and 2, the plates at and b m The object ture as in the ordinaryway of running a carsilicon carbide which comprises heating.

borundum furace and the furnace run for its correct length of time andenergy input and when the plates 6 and a are removed it will be foundthat they have joined together due to crystalline growth between the twoplates at the joint 0.

These plates such as a and b may be either placed in the furnace in thegreen form, that is to say finely crushed carborundum crystals bondedtogether with some temporary bond such as glue, in which case only theplate 6 and the part of plate a inside the crystalline zone whoseboundary is 6 would be recrystallized. The plate outside the boundary ewould be still in an unrecrystallized condition, that is to say thecrystals in the plate at this point would still retain the.

original size of the crystal particles as used in molding the greenplate and would not be bonded together. i

The plates a andb might also be first recrystallized separately or theplate (1 might be recrystallized and the plate I) might be a greenplate. This would depend entirely upon the size, shape and convenienceof handling the plates a and b.

In the form shown in Figs. 3 and 4 the procedure would be similar to theone already described in connection with Flgs. 1

' and 2. The plates at and 6?) would be first joined and then the hollowtrough would be turned upside down and the plate a would.

them in. contact with one another to a temperature of approximately 1800C. or over, in a non-oxidizing atmosphere.

2.-The method of uniting two pieces of recrystallized silicon carbidewhich comprises heating them in contact with one another to atemperature of approximately 1800 C. or over in a non-oxidizing atmos-.phere in the presence of carbon.

I 3. The method of uniting and recrystallizing two pieces of moldedunrecrystallized silicon carbide which comprises heating them in contactwith one another to a temperature of approximately 1800 C. or over,]

1n a non-oxidizing atmosphere.

4. The method of uniting and recrystallizing two pieces of moldedunrecrystallized silicon carbide which comprises heating them in contactwith one another to a temperature of approximately 1800 C. or over in anon-oxidizing atmosphere in the pres: ence of carbon.

5. The method of uniting two pieces of silicon carbide which consists ofplacing said pieces in substantial contact with one another with finelydivide-d carborundum between their contacting faces, and heating thepieces while so positioned to approximately 1800 G.;or over.

6. The method of uniting two pieces of silicon carbide which consists ofplacing said pieces in substantial contact with one another withcarborundum mix between their contacting faces, and heating the pieceswhile so positioned to approximately 1800 C. or-over.'

7. The method of uniting two pieces of silicon carbide which consists ofplacing said pieces in substantial contact with one another withcarbonaceous material between their contacting faces, and heating thepieces whileso positioned to approximately 1800 C. or over.

silicon carbide which consists in placing said pieces in substantialcontact with one another with carbonaceous material between theircontacting surfaces, and raising the temperature of said surfaces toapproximately 1800 C. or over by a flow of heat in a directionsubstantially at right angles to said surfaces.

9. The method of uniting two pieces of silicon carbide which consists inplacing said pieces in substantial contact with one another withcarborundum' material "between their contacting surfaces, and raisingthe temperature of said surfaces to a proximately,'1800 C. or over by aflow of eat in a direction substantially'at right angles to saidsurfaces.

10. The method of uniting and recrystallizing two pieces of moldedunrecrystallized sil con carbide which consists in placing said piecesin substantial contact with one another with carbonaceous materialbetween their. contacting surfaces and raising thev until the same isconverted into crystalline carborundum. v V p 12. The method of unitingand recrystallizin two pieces of unrecrystallized carborun um whichconsists in mounting said I pieces in a furnace in contact with oneanother, embedding the pieces in carborundum .8. The method of unitingtwo pieces of 9 7 mix and heating the furnace until the mix is convertedinto crystalline carborunduin.

13. The method of forming a structure by uniting several pieces ofcarborundum which consists in placing a plurality of said pieces incontact in a furnace and embedding the portions of said pieces adjacenttheir contacting surfaces in carborundum mix, heatborundum in contactvwith the structure so formed and uniting said other piece thereto byembedding and heating as above set forth.

JAMES KELLEHER.

